My garage is an attached 2 car garage with drywalled walls and ceiling. It has a 4:12 pitch roof with a shallow attic. The drywall ceiling has been showing spots of dimpling, seams splitting, and other moisture/heat related(?) symptoms that appeared this year (been here for 6 years). There are no water stains on the ceiling, just the bubbling and seam failures. The roof has a ridge vent the entire length of the roof (21 or so feet).

Any suggestions for tests/things to observe when I venture up in the attic would be much appreciated!

The exterior roof/shingles are in good shape. The garage door is open most days (except when it is raining) to let the heat out but perhaps that is contributing to or causing the ceiling issues? With the door closed, it is stifling hot in the garage.

Thanks in advance.

 

You mention ridge vent but are there soffit vents as well?

I can see that you might have some damage due to humidity if the door is open a lot, especially in the summer.

 

Was the drywall primed/painted? Unsealed drywall and joint compound will absorb humid air and deteriorate over time.